Web fs image links

This is in develop as https://github.com/openmicroscopy/openmicroscopy/pull/672. In order to keep the UI code identical between FS and dev_4_4 branches, this branch should also be in dev_4_4, with the Blitz image.countFileSetFiles() and image.getFilesetFiles() returning nothing.

This PR shouldn't change the behaviour of the non-FS webclient.

NB: https://github.com/will-moore/openmicroscopy/commit/eab8873d98d908c66328ae2b20434956d3de09af needs to be ported back into develop, so that we don't display the file paths of pre-FS original (archived) files.